Recently, in the field of recording devices such as a hard disk drive, it is more and more demanded to reduce the size of the hard disk drive and to increase its recording density. A perpendicular recording system is proposed as one of the approaches to increase the recording density of a recording medium. This system is attracting attention as a system replacing the longitudinal recording system.
A technology combining the perpendicular recording system with a head utilizing the magnetoresistance effect, such as an MR or a GMR head, has also been proposed. An article by the inventors of the present invention, "Perpendicular Magnetic Recording Using a Single-layer Medium and a Merged MR Head", Journal of the Magnetics Society of Japan, Vol. 19, Supplement, No. S2, 1995, reports characteristics of a single-layer Co--Cr perpendicular film as a recording medium which is indented to apply a merged MR head to a perpendicular recording system without modifying its write section. The composition of the single-layer Co--Cr perpendicular film described in the article has Co content of 78 at. % and Cr content of 22 at. %.
However, research by the inventors of the present invention revealed that the single-layer Co--Cr film consisting of the Co content of 78 at. % and the Cr content of 22 at. % used in the above conventional technology cannot provide sufficient maximum perpendicular magnetic interaction (.DELTA.M.perp.).sub.max when an MR head is used as the reproducing head. In view of the foregoing, the inventors of the present invention have continued their research and have found that the Co--Cr film exhibits unique (.DELTA.M.perp.).sub.max properties in a specific range of the contents of Co and Cr, within which the film has excellent properties as a perpendicular magnetic recording medium for an MR head.
Thus, the object of the present invention is to provide a perpendicular magnetic recording medium with favorable magnetic properties when a head utilizing the magnetoresistance effect is used.